The Methods of Enumeration in Microbes

••• gorodenkoff/iStock/GettyImages

The methods of enumeration in microbes can be divided into four categories. Direct methods involve counting the microbes, while indirect methods involve estimation. Viable methods only count cells that are metabolically active, while total counts include dead and inactive cells.

Direct/Viable

A direct/viable method involves a standard plate count, in which repeated dilutions of a sample are counted to calculate the count in the original sample.

Indirect/Viable

Indirect/viable methods such as MPN (most probable number) involve making a statistical inference about the microbe count based on patterns of growth.

Direct/Total

The microbes are counted with the aid of fluorescent stains and dyes, which make the microbes visible with the aid of a fluorescent microscope.

Indirect/Total

Spectroscopy is a form of indirect/total enumeration, which involves estimating the amount of microbes based on the amount of light passed through the culture by a spectrophotometer.

Related Articles

What Is Enumeration in Microbiology?
What Is a CFU in Microbiology?
Microbiology vs. Biochemistry
How to Count Colonies in Microbiology
The Advantages of Stained Bacteria
The Microorganisms Found in Sewage
What is Turbidity & What Does It Indicate in Microbiology?
How to Calculate the Corrected WBC Count
How to Change 1/4 to a Decimal Form
The Role of Microbes in Industry
How to Calculate the Percent Weight Per Volume
How to Calculate PPB
How to Calculate CFU From Dilution
How to Calculate the Rate of Decay
How to Make Agar Plates
How to Calculate Absorbance
How to Calculate Rate of Decrease
How to Measure Bacterial Growth in Petri Dishes
The 3 Types of Bacteria
How to Calculate Recombination Fraction